~ Sumaya Beri | 11C
Once upon a time, anywhere from 5 to 7 centuries ago, a mass epidemic killed hundreds of people. Their main symptom? Dancing. In Strasbourg 1518, Frau Troffea started dancing in the middle of the street. She was unable to stop. Even when exhaustion overtook her, she continued to dance for days with only short rests in between. Soon, other people began to join in. Some danced so much that they broke their ribs, collapsed out of exhaustion, suffered strokes and an undocumented number (possibly surpassing 400) of people even lost their lives. Each patient’s dance was uncontrollable and unintended. There was no useful information about dancing mania at the time, despite a similar dancing plague having occurred as far back as 1374 and then again in 1463. Frau Troffea was taken to the shrine of St Vitus (the patron of dance) for treatment. Some authorities believed he could be the cure while others believed a specific type of music was the answer. But, because no one knew its cause, no one could treat it. Doctors at the time diagnosed it to be overheated blood. Some thought it pointed towards demonic possession. Even today, as scientific advancements transcend all ancient expectations, we are unable to point out a direct cause. The infection may have been brought on by a fungus known as ergot, which is now known to lead to hallucination and neurological disturbances. It may just have been mass hysteria caused by stress. However, we now believe a disease called Sydenham’s Chorea to be the most probable source. The disease is also known as St Vitus’ dance, referencing the great plague of 1518. Sydenham’s chorea is an early onset neurological disease resulting from infection by Group A beta-hemolytic streptococcus. It is a type of autoimmune disease, with the infectant bacteria causing rheumatic fever, and most notably, uncontrollable, rapid, irregular movement of the limbs and facial muscles. Writhing movements in this disease are due to the reaction of one’s immune system to the bacterium interfering with the basal ganglia- the part of the brain that controls motor movements through promotion and inhibition of movement in other parts of the brain itself (i.e., the motor cortex, etc). Infection leads to the generation of an antibody response by streptococci antigens. Due to antigen mimicry, and a phenomena known as cross reactivity, where foreign antigens appear similar to the body’s own immune system, stimulated antibodies begin to attack the body instead of the bacterium. They tend to target the basal ganglia, specifically a section of it known as the corpus striatum, which is an important site for reception of chemical inputs (glutamate, dopamine etc.) and hence, a critical part of the motor system of the brain. The reaction of the antibodies causes inflammation in the striatum, mainly in a structure known as the Caudate nucleus (C-shaped, tail-like) which contains dopaminergic neurons. The inflammatory process causes an imbalance among the dopaminergic system and other chemical systems in the nervous system (cholinergic system, inhibitory gamma-aminobutyric acid (GABA) system). This in turn, leads to abnormalities in the motor system of the body- leading to the jerking, uncontrollable movements characteristic of the St Vitus’ dance. While Sydenham’s Chorea may well have been the perpetrator, it is unlikely to have affected so many adults in such a short time frame. No matter how close we get to the answer, the true cause of the ancient dancing plagues remains a mystery.